Could something even smaller than a pea end a horse's athletic career? If that something is a cystic lesion in the stifle (or femoral condylar cyst), it's entirely possible. Fortunately, specific management approaches can help some horses return to their jobs in the arena or on the track with few, if any, lasting effects.

Wayne McIlwraith, BVSc, PhD, Dipl. ACVS, ACVSMR of the Colorado State University Equine Orthopaedic Research Center, in Ft. Collins, described stifle bone cysts at the 2013 American Association of Equine Practitioners' Convention, held Dec. 7-11 in Nashville, Tenn., in the “Lessons Learned ” session. The stifle consists of several different joints between the patella (knee cap), the femur (the long upper bone of the hind leg), and the tibia (the inner of the two bones that extends down from the knee to the hock).

McIlwraith emphasized that there are five different types of cystic lesions that arise in the stifle joint ranging from dome-shaped deficits to circular ones. Historically, clinical signs tend to recur following treatment when the horse returns to its previous athletic level.

In general, McIlwraith noted that intra-articular (in the joint) corticosteroid injections tend to be unrewarding. Surgeons performing arthrotomy (opening up the joint) with debridement of the cystic lesion have experienced a relatively high success rate, but the procedure is quite invasive. Instead, they often debride the lesion arthroscopically and inject corticosteroids directly into the cystic lesion with success; sometimes they augment this approach by adding a bone graft over the lesion. Another treatment option that shows promise is the placement of a stainless steel lag screw across the condyle through the cystic lesion